The figures referred to are calculated as generation from onshore wind, multiplied by carbon dioxide emissions per GWh of electricity supplied from all fossil fuels. The quoted 6.3 million tonnes figure in 2011 has been revised to 6.4 million tonnes. As with the data gathered for all power generation technology, it does not include emissions from construction or grid connection.
Onshore wind power has a very small carbon footprint range relative to other energy generation technologies: between 8 and 20g CO2eq/kWh, taking into account emissions incurred during the manufacture, construction and decommissioning phases. The average emissions from fossil-fuelled power generation in the UK is around 700gCO2/kWh.
Back-up generation—including generation from gas, coal or biomass—is sometimes required to balance intermittent renewable generators as well as to cover demand spikes and other station outage. DECC has not estimated the gas turbine energy contribution (and therefore related CO2 emissions) to manage wind variability specifically, due to complex inter-dependencies of the power system operational parameters.1
1 Estimates of wind generation and CCGT emissions are taken from scenarios modelled for the Electricity Market Reform Delivery Plan. Please see:
A range is given based on the range of generation estimates for onshore and offshore wind in the modelled scenarios. Estimates for onshore wind include both large and small scale.